The present invention relates to a strip wound hose comprising a metal band having an approximately S-shaped profile, which is wound in helical windings to form a hose. The profile of the metal band exhibits two wall sections, essentially extending axially and radially spaced apart from each other, which are connected to each other by a web and respectively provided at their edges with a bent rim. The profiles of two adjacent windings of the strip wound hose are mutually interlocked via their rims such that they are axially mobile between a compressed position and an extended position.
The invention further relates to a method for widening and/or cutting to length such a strip wound hose.
Strip wound hoses of the above-mentioned type have been known for quite some time. The axial mobility of the individual windings in reference to each other provides the strip wound hoses with great mobility, yet still showing high mechanic strength of the profiled windings. For the production of such strip wound hoses, initially a metal band is deformed by profiling via several pairs of profiled rolls into an essentially S-shaped profile such that particularly the edge of the rims are angularly aligned opposite each other. The profiled metal band is then wound onto a rotating winding mandrel, with the oppositely angled rims each loosely engaging two adjacent windings.
Strip wound hoses are known from prior art with their windings having a hook-shaped profile. The band edges of the profiled metal band are here simply folded so that bent rims develop, loosely interlocked with adjacent windings. The individual windings loosely engage each other and can move in reference to each other axially between the compressed position and the extended position. Strip wound hoses with a hook-shaped profile show the greatest mobility among the strip wound hoses.
Additionally, strip wound hoses are known from prior art with their adjacent windings being loosely rebated to each other by the profiled metal band showing the form of a rebated or agraffe profile. Here, the rims of the metal band profile are not only bent in one direction, but also bent reversely to a certain extent so that they mutually engage loosely with appropriately reversely bent rims of an adjacent winding and form a type of mobile form-fitting connection.
In strip wound hoses with rebated or agraffe profiles, the profiles of two adjacent windings can also move axially between a compressed position and an extended position. The mutually rebated profile however significantly limits the axial path of motion and the internal friction between the individual windings moved axially in reference to each other is several times higher than that of a hook-shaped profile. In return, a strip wound hose with a rebated or agraffe profile is more resilient than a strip wound hose with a hook-shaped profile and can easily be mechanically widened, for example.
The higher mobility and lower interior fraction of a strip wound hose with a hook-shaped profile is desired for many applications of strip wound hoses. Only as an example, here the use of a strip wound hose is mentioned within a flexible conduit for the exhaust system of a motor vehicle, described for example in DE 103 40 983 A1. Here the strip wound hose is used as a liner inside a metal bellows for conducting the flow of the gases guided through. In addition to conducting the flow, the liner also serves for the thermal protection of the metal bellows from the generally very hot exhaust from the internal combustion engine guided through.
Here, the connection of the strip wound hose inside the flexible conduit is problematic. By the coaxial arrangement of the liner and the metal bellows the liner must be widened in the proximity of the rims of the metal bellows in order to allow fastening it directly or indirectly at the rims of the bellows. The widening of the strip wound hose with a hook-shaped profile is however most problematic, because here the risk is given that adjacent windings involved can disengage and lose their mutual grip.
This problem is given in all strip wound hoses with a hook-shaped profile, which are widened, regardless of their respective application. Furthermore, strip wound hoses with a hook-shaped profile, which are commonly produced and transported as bulk goods and cut to length for the production of a conduit, show the unpleasant feature that a simple cut leads to projecting ends (gores), which are problematic for further processing.
Both when cutting as well as when widening strip wound hoses with a hook-shaped profile here particular provisions must be implemented, such as the use of additional sheaths, for example.